Device for gauging the cutting of rafters



Feb. 8, 1938. 5.o, KARLsoN DEVICE FOR GAUGING THE CUTTING OF' RAFTERS BY*MPW ATTORNEYS Patented Feb. 8, 1938 UNITED STATES PATENT OFFICE DEVICEFOR GAUGING THE CUTTING OF RAFTERS 3 Claims.

This invention has relation to carpenters implements and comprehends animproved device for facilitating the computation or determination of thelengths and angles of rafter cuts.

The invention broadly aims to provide a device of the indicatedcharacter by means of which the vaverage carpenter may expeditiouslycompute and with the aid of the usual steel square mark the lumber forthe various cuts to be made in Aiashioning common rafters, hip andvalley rafters, and jack rafters.

More particularly the invention resides in a device of the character setforth and for the purpose specified which includes a base havinggraduations, lines and indicia on one surface thereof and cooperativegraduated sliding and swinging members adjustable to positionscoinciding with the building and roof measurements to compute anddetermine the lengths of the various rafters and the heel, plumb andangle cuts to be made.

Other objects of the invention reside in the provision of a device ofthis character which is comparatively simple in its construction andmode of use, inexpensive to produce, highly efficient in its purpose andwhich is small and compact whereby it may be readily carried in thecarpenters kit or pocket.

With the above enumerated and other objects in view, reference is nowmade to the following specification and accompanying drawing in whichthere is disclosed a preferred embodiment of the invention, while theappended claims cover variations and modifications thereof which fallwithin the scope of the invention.

In the drawing:

Fig. 1 is a face view of the device constructed in accordance with theinvention, illustrating the slide member and pivoted arm in adjusted setposition.

Fig. 2 is an end edge view thereof as viewed from the left hand edge ofthe device.

Fig. 3 is a face view illustrating the slide member and pivoted arm infolded inactive compact position for storage of the device.

Fig. 4 is` a vertical sectional view taken approximately on. the line4--4 of Fig. 3.

Referring to the drawing by characters of reference, Ill designates thebase of the devicel which is preferably of rectangular configurationhaving parallel opposite longitudinal side edges Il and I2 and a planeupper surface I3 which is provided with a longitudinally extending lineI4 adjacent to and parallel with the side edge I2 and adjacent one endedge with a perpendicular transverse line I5. The line I4 is subdividedby longitudinally spaced graduations I6 having associated indicia Ilbeginning at the line I5.

A pair of longitudinally extending lines I8 and I9 are also inscribed onthe upper surface I3 and 5 said lines are parallel to each other and tothe line I4. The line I8 has associated therewith indicia 2E) which ishere designated common rafter, while the line I9 has associatedtherewith indicia 2l, here designated hip or valley mi rafter. The lineI4 together with its graduations I5 and indicia I'lhas further indicia22 associated therewith designated the rise,

A slide member designated generally by the reference character 23 ismounted for guided 1P sliding movement with reference to the base I0 andsaid member 23 is preferably of T-shaped construction having alongitudinally extending head 24 which is formed with a groove 25 in itsinner edge to slidably fit over the side edge I2 of the base. The slidemember 23 further includes a slotted arm 26 disposed at an angle to thehead 2li and extending transversely of the base I0 with the basereceived by the slotted portion so that the arm 26 straddles the same,and the upper surface of the portion of the arm 26 which overlies thebase is provided with a series of graduations 2l which start at the lineIII and extend throughout its length to the free end thereof. Indicia 28is associated with the grad uations and the arm 26 is also provided withindicia 29 designated the run. In order to lock the slide member 23 inadjusted relation to the base, a set screw 30 having a knurledmanipulating head 3l is threaded through the outer end edge of the slidearm 26 and is designed to be impinged against the side edge'l I of thebase.

The device further includes a swinging arm 32 which is mounted to swingon a pivot 33 having a vertical axis located at the intersection of thelines i4 and I5 adjacent one corner of the base, the edge 34 of theswinging arm intersecting the axis of the pivotal connection of the armand said edge being provided with a line of graduations 35 andassociated indicia 3S starting at the pivotal point of the arm.

The arm is disposed between the resilient furcations of a bracket 3l andthe arm is secured in adjusted angular position by means of a thumb nut38 which threadedly engages the pivot 33 for 50 frictionally clampingthe arm between the furcations. In order to limit the swinging of thearm 32 to a position parallel with the head 24 of the slide member, aclip 39 is provided on the head 24 of the slide member.

ione-half inches.

The upper plane surface I3 of the base is provided with curved lines 4Dand 4I which extend from the axis of the pivot 33, diverge withreference to each other and terminate at the oppositeY end edge of thebase. These curved lines are respectively designated by the indicia 42and 43 as bevel for hip or valley rafter and bevel for jack rafter.

In use and operation, when it is desired to determine the length of acommon rafter and the angle ofthe heel and plumb cuts thereof, the slideis first moved so that the graduated edge of the slide arm coincideswith the graduation I6 and indicia Il corresponding to the rise of theroof. Y The set screw 30 is then tightened to retain the adjustment andthe swinging arm 32 is then swung to a position where its graduated edgecoincides with the graduation 2l and indicia 28 which corresponds to therun which is half the width of the building. The graduation 35 andindicia 35 on the swinging arm 32 at the point of intersection of thegraduated edges of the arms 26 and 32 will give the length of therafter. By use of the usual carpenters steel square, the angles of theheel and plumb cuts and the bevel cuts for roofs of equal pitch areobtained as follows: Assuming that the run is fifteen feet and the risefourteen feet, first set the slide member at the base graduation I6indicated by the indicia il as fourteen, then tighten the set screw 3l?.The swinging arm 32 is then adjusted at an angle where its-edge 34intersects the graduated edge of the arm portion 26 of the slide member23 at the graduation 21 which correspends to the run, namely fifteenfeet. The graduation 35 indicated by the indicia 36 on the swinging arm32Will indicate the length of the common rafters, namely twenty feet,six and For the purpose of obtaining the heel and plumb cuts so that thegraduation marked twelve on the blade of the steel square may be used asone measurement, tighten the clamping nut 38 to retain the swinging armin set position and move the slide until the graduated edge thereofcoincides with the intersection of the graduated edge 34 with the commonrafter line i8 and tighten the set screw 30. The swinging arm^32 is nowreleased and swung to the out-of-the-way position illustrated in Fig. 3of the drawing and the base graduation where the slide member arm 26 isnow adjusted will givethe other reading as eleven and one-quarter inchesfor the steel square tongue. When the steel square is placedv on vthelumber with the twelve inch blade graduation at one edge of the lumberand the eleven and one-quarter inch tongue graduation at the edge of thelumber, the marking of the lumber along the edge of the blade will givethe heel out while the marking of the lumber along the edge of thetongue will give the plumb cut.

To'determine the heel vand plumb cuts for the valley rafter, read thegraduation at the point of intersection of the hip or Valley rafter linedesignated i9, with the slide arm 26, and the reading for the steelsquare will then be eleven and one-quarter inches on the tongue andseventeen inches on the blade, thelatter being the reading shown at thehip and valley rafter line.

To determine the setting of the steel square for the bevel cut of a hipor valley rafter, read the graduation on the slide arm 26 at theintersecton with the curved line designated bevel for hip or valleyrafter which, in the example given, will be found to be nine andthreeeighths inches which combined with the base graduation at theintersection of the slide arm 26, is eleven and one-quarter inches. Thesteel square is then laid on the edge of the lumber and marked along thetongue of the steel square.

The plumb cuts at the opposite endsV of the jack rafters are the same asthaplumb cuts for the common rafter and the bevel of the lower plumb cutwhich is to rest against the side of the valley rafter is obtained byreading the base graduation which shows eleven and one-quarter inchesand the slide graduation at the intersection of the curved line markedbevel for jack rafter which is found to be eight and one-quarter inches.

In order to determine the length of the valley rafter, adjust theswinging arm 32 to the point of intersection of the graduated edge ofthe slide arm with the line i9 designated hip or valley rafter andtighten the clamping nut 38. Then move the slide to the base graduationI6 which corresponds to the rise of fourteen feet and read thegraduation 35 on the swinging arm 32 at the point of intersection of thegraduated edge of the slide arm 26 with the swinging arm 32. This, inthe example being given, will show twenty-ve feet, six inches.

To determine the difference in length between the common rafter and therst jack rafter, move the slide arm 26 to the base graduation eleven andone-half, set therrswinging arm 32 yto the point of intersection of theline 4|, designated bevel for jack rafter, tighten the swinging arm inthis position and then move the slide arm, 26 to the point where itintersects the edge 34 of the swinging arm 32 at the graduation 2l onthe slide arm which corresponds to the spacing of the jack rafters,which spacing has been predetermined, say for example, as sixteen inchesapart. By then reading the graduation I6 and indicia il on the base atthe intersection of the graduated edge of the slide arm, the differencein length between the common rafter and the first jack rafter, as wellas between each of the succeeding jack rafters, will be obtained ininches and Will in the example given be twenty-one and seven-eighthsinches.

What is claimed is:

l. In a device for computing rafter cuts, a base having a plane uppersurface, a slide member overlying and extending across the upper sur`face of the base, vmeans mounting the slide member for guided slidingmovement lengthwise of the base, an arm pivoted adjacent one corner ofthe base, means for locking the slide member and arm respectively inadjusted relation to each other, and curved lines on the surface of thebase extending from the pivotal point of the arm for obtaining readingsto determine the angle of the bevel cuts for the hip or valley and jackrafters.

2. In a device for computing rafter cuts, a rectangular base having asurface inscribed with lines and indicia, a T-shaped slide member havinga slotted arm portion straddling and extending across opposite surfacesof said base, graduations and indicia on the surface of the arm portionoverlying the inscribed surface of the base, a slotted head portion ofsaid slide member engaging over one edge of the base for mounting theslide member for guided sliding movement lengthwise of the base, an armpivoted adjacent one corner of the` base having graduations and indiciathereon, and means for locking the slide member and arm respectively inadjusted relation to each other, the lines on the surface of the basebeing so arranged as to beintersected by the slide member and thepivoted arm for designating the points of reading of the graduations todetermine the length of common, hip and valle-y rafters and 5 the anglesof the cuts to be made.

3. A device for computing rafter cuts including a base having a planesurface bearing a length- Wise line having graduations for indicatingthe rise, a pair of parallel lines spaced therefrom and 10 from eachother for use in computing the cuts of common rafters and hip or valleyrafters respectively, and divergent curved lines ,for use in computingthe bevel cuts of the jack rafters and hip or Valley raftersrespectively, a slide member overlying the surface of said baseextending thereacross perpendicular to the parallel lines, mounted forguided sliding movement lengthwise thereof and having graduationsindicating the run and cooperating With said parallel and curved linesto compute said rafter cuts, a graduated arm pivoted to said base at theintersection of the curved lines with each other and with the graduatedline indicating the rise for the purpose of computing the length of therafters, and means for locking the slide member and arm respectively inadjusted positions.

ERIK O. KARLSON.

